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Fig. 1.9 The giant centriole (proximal centriole) and primary cilium (distal centriole) of fly
spermatocytes: A-J serial section electron microscopy analysis of a pair of giant centrioles
organized in an orthogonal relationship. k The cross-section of the daughter centriole from c is
magnified to demonstrate triplet microtubules. j The last cross-section is highlighted to depict the
presence of irregular numbers of doublet microtubules in the primary cilium. TF, transitional
fibers connecting the centriole to the plasma membrane; TM, triplet microtubules; DM, doublet
microtubules; CM, cilium membrane; pc and dc according to Tates: pc, proximal centriole or
basal body and dc, distal centriole
Fig. 1.10 Round spermatids formed imminently after meiosis, contain a white nucleus (N) and
dark mitochondria (M) of similar size (a). Centriolar mutants in the spermatid state form nuclei
and mitochondria of variable size (b and c)
those of other organisms (Blachon et al. 2009 ; Mottier-Pavie and Megraw 2009 ;
Tates 1971 ). At particular stage of spermiogenesis these giant centrioles are sur-
rounded by a long and thick PCM (also referred to as the ''centriolar adjunct'').
These centrioles provide a very convenient model to study centriole elongation
and several mutants that have shortened giant centrosomes have been described.
Proteins essential for giant centriole elongation include: Bld10, Poc1, and Sas-4
(Blachon et al. 2009 ; Mottier-Pavie and Megraw 2009 ).
Fifth, during spermiogenesis, the spermatid cell forms a centriole precursor-like
structure called the PCL (Fig. 1.11 a). The PCL has been proposed to be a centriole
intermediate that arrests at the stage before the centriolar microtubules are
assembled. Therefore, by studying how the PCL forms, one can study the early
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